TITLE 77: PUBLIC HEALTH
CHAPTER I: DEPARTMENT OF PUBLIC HEALTHSUBCHAPTER r: WATER AND SEWAGE
PART 890
ILLINOIS PLUMBING CODE
SECTION 890.1600 SPECIAL VENTING FOR ISLAND FIXTURES

Section 890.1600 Special
Venting for Island Fixtures

a) Traps for island sinks and similar equipment shall be roughed
in above the floor and shall be vented by extending the vent as high as
possible, but at least the drainboard height, and then returning it downward
and connecting it to the horizontal sink drain immediately downstream from the
vertical fixture drain. Back-to-back island vented fixtures shall meet the
requirements of Section 890.1480(b).

b) The returned vent shall be connected to the horizontal drain
through a sanitary drainage fitting and shall be provided with a vent taken off
the vertical fixture vent by means of a sanitary drainage fitting immediately
below the floor and extending to the nearest partition and then through the
roof to the outside atmosphere, or may be connected to other vents at a point
at least 6 inches above the flood level rim of the fixture served. Drainage
fittings shall be used on all parts of the vent below the floor level, and a
minimum grade of ¼ inch per foot back to the drain shall be maintained. The
returned bend used under the drainboard shall be a one-piece fitting or
assembly of a 45 degree, a 90 degree, and a 45 degree elbow in the order named.
(See Section 890.1340 and Appendix K.Illustration GG.)